The invention relates to a stabilizer assembly unit for a motor vehicle, including a first fluid pressure actuator and a second fluid pressure actuator which are associated with opposite ends of an antiroll bar.
Such stabilizer assembly units are used in active chassis for suppressing or controlling the roll movements of the vehicle body in cornering. In these arrangements the use of an antiroll bar that is passive when taken by itself has been known for a long time. Such an antiroll bar is comprised of an elastic middle section that is rotatably attached to the vehicle body, and two levers that are connected to the wheel suspensions. Now if the vertical distance between the vehicle axle with which the antiroll bar is associated and the vehicle body changes on one vehicle side as compared to the other vehicle side, the antiroll bar is increasingly elastically tensioned as the change in distance increases. This results in a roll torque which attempts to urge the vehicle body into a position in which both ends of the vehicle axle have the same distance to the vehicle body.
A basic disadvantage of the sole use of such antiroll bars is that the latter impede cushioning movements of the axle on one side, which are for example necessary in the case of an uneven road on one side.
The active chassis already mentioned serve to solve this problem. In these active chassis, the chassis characteristics are changed with the aid of actuators in response to vehicle parameters and a particular traffic situation by, for example, pretensioning or relieving antiroll bars. This results in an improved adaptation of the vehicle to the respective traffic situation, such as an improved road grip when cornering.
DE 44 43 809 A1 discloses, for example, a stabilizer assembly unit including an antiroll bar that is configured in two parts and the ends of which may be tensioned with respect to one another by means of a hydraulic rotary drive. Such rotary drives have to be produced with close tolerances and sealed in a complicated manner. Therefore, they are expensive. They are, moreover, relatively maintenance-intensive and susceptible to faults in operation.
The generic document WO 02/083439 A1, and corresponding U.S. Pat. No. 7,055,832 B2, both of which are incorporated by reference herein, shows a stabilizer assembly unit including an antiroll bar which may be connected to the wheels via two linear hydraulic actuators. Each of the hydraulic actuators configured as a piston/cylinder unit disposes of two pressure connections via which the two cylinder chambers existing in each actuator may be acted upon with pressure. Provided for this purpose are one or several control valves, a plurality of hydraulic lines, and a hydraulic pump having a reservoir associated therewith, these components forming a comparatively complicated arrangement with a space requirement that should not be neglected.